Arrays of optical fibers having angled end faces are desirable for a wide variety of applications. An array of optical fibers having angled end faces generally includes a ferrule and a plurality of optical fibers mounted within the ferrule. These arrays may utilize various types of multifiber ferrules including ferrules having conventional form factors such as MT ferrules or v-groove ferrules. As is known, MT ferrules generally define a plurality of cylindrical bores through which the optical fibers extend, while v-groove ferrules typically consist of a pair of ferrule halves formed of silicon with at least one and, more typically, both of the ferrule halves defining a plurality of lengthwise extending grooves, such as a plurality of lengthwise extending v-shaped grooves. Regardless of the form factor, the optical fibers are mounted within the ferrule, such as by extending through the bores or the grooves defined by the ferrule. The optical fibers are mounted within the ferrule such that end portions of the optical fibers protrude beyond the front face of the ferrule. Moreover, the end faces of the optical fibers that protrude beyond the front face of the ferrule are angled relative to the longitudinal axes defined by the optical fibers. While the end faces may be disposed at a variety of angles, the end faces are typically disposed at about an angle of 45° relative to the longitudinal axes.
Arrays of optical fibers having angled end faces can be utilized to couple optical signals between various devices, such as various optoelectronic devices, including, for example, a photo-diode array or an array of vertical cavity surface emitting lasers (VCSELs). As shown in FIG. 1 in which the optoelectronic device is an array of VCSELs 10, the VCSELs emit optical signals perpendicular to the plane defined by the substrate 12 upon which the VCSELs are mounted. The optical fibers 14 receive the optical signals emitted by the array of VCSELs via the angled end faces 16 as described below. The optical fibers generally extend to and are in communication with another device, such as another optoelectronic device including, for example a photodetector array, i.e., a receiver. Thus, this array of optical fibers facilitates communication between the VCSEL-based transmitter and the photodiode receiver.
In the absence of an array of optical fibers having angled end faces, the optical signals emitted by the VCSEL array would generally be coupled to optical fibers having end faces that are parallel to the VCSEL or the surface plane of the photodetector. These fibers would therefore extend perpendicularly from the VCSEL or photodetector array. By utilizing an array of optical fibers having angled end faces as shown in FIG. 1, however, the array of optical fibers may be positioned in a generally horizontal plane relative to the VCSEL array such that the angled end faces of the optical fibers are disposed in alignment with respective optical signals emitted by the VCSEL array. Advantageously, the spacing between the end faces of the optical fibers and the VCSEL array may be quite small, such as 50-100 microns, thereby potentially reducing the size and profile of the resulting package. The optical signals emitted by the VCSEL array propagate through the side surface of respective optical fiber and are internally reflected by the angled end face so as to then propagate lengthwise along the optical fiber. Thus, the angle at which the end faces are disposed relative to the longitudinal axes of the optical fibers may vary, but is generally defined by Snell's law, such that the optical signals are totally internally reflected within the optical fibers. In addition, the spacing between the optoelectronic devices and other devices, such as application specific integrated circuits (ASICs), associated with the optoelectronic devices is minimized, thereby allowing shorter electrical bond wires. These bond wires electrically connect the VCSEL and/or the photodiode array with the ASIC. Shorter bond wires correspondingly reduce parasitic capacitance and induction and their deleterious effects upon the optical signal. Thus, the resulting optoelectronic circuit can generally operate at greater speeds as desired for Fibre Channel and gigabit Ethernet.
Arrays of optical fibers having angled end faces have generally been fabricated in two different manners. According to one technique, each optical fiber is individually polished such that the end face has a predefined angle relative to the longitudinal axis of the optical fiber. The optical fibers that have been individually polished are then mounted within a ferrule such that the angled end faces protrude beyond the front face of the ferrule by a predefined distance. As will be apparent, the individual polishing of each optical fiber can be a time-consuming process and typically requires substantially consistent polishing operations such that each optical fiber has an end face disposed at nearly the same angle.
Instead of individually polishing the optical fibers, the optical fibers can be mounted within a ferrule such that end portions of the optical fibers protrude beyond the front face of the ferrule by at least a predetermined distance. Thereafter, the end faces of the optical fibers may be concurrently polished until the end faces define the desired angle relative to the longitudinal axes of the optical fibers. Unfortunately, an error that occurs during mounting of the optical fibers or polishing of the optical fibers that may affect only one or a small number of the optical fibers will generally cause the entire array to be scrapped even though other optical fibers may have been appropriately mounted and polished, thereby disadvantageously increasing the cost of the resulting arrays of optical fibers having angled end faces. For example, if the tip of a single optical fiber is broken during the polishing process, the entire array may have to be scrapped even though the other optical fibers are acceptable.
As such, it would be desirable to develop an improved method for fabricating an array of optical fibers having angled end faces, especially in light of the increasing demand for these arrays for use with VCSEL arrays, photodiode arrays and other optoelectronic devices.